In a Citizens Broadband Radio Service (CBRS) network. Citizens Broadband Radio Service Devices (CBSDs) serve as access points or base stations which can support wireless communications with user equipment devices (UEs).
A CBRS network often includes one or more Citizens Broadband Radio Service Devices (CBSDs) with relatively small coverage areas as compared to a macro base station or access point. The CBSDs are used to provide services to subscribers' user equipment devices. Spectrum is granted to each of the CBSDs using a centralized system called the Spectrum Access System (SAS). The Spectrum Access System is a central processing and database system that receives and processes spectrum grant requests. In the CBRS network, interference is managed through power management of CBSD devices by the Spectrum Access System (SAS). The SAS stores information regarding which CBSD uses how much spectrum at which location in the CBRS network. The objective of the SAS is to allocate spectrum in the most efficient and effective manner as possible. As the CBRS' network frequency spectrum is a limited resource, the SAS divides up the frequency spectrum into spectrum bands, e.g., frequency bands, which are assigned to different CBSDs. Each CBSD having its own cell area or coverage area in which it transmits. However, because the available frequency spectrum is limited the SAS reuses the same frequency spectrum, i.e., SAS assigns the same frequency spectrum also referred to as a channel to multiple CBSDs which are located in different cells. This reuse of the same transmission channels or frequency spectrum by multiple CBSDs gives rise to co-channel interference. Co-channel interference occurs when multiple wireless transmissions occur on the same channel in the same area. For example, a first user equipment device communicates in a first cell transmits a first signal to a first CBSD using a first channel or frequency but signals at the same frequency (co-channel signals) from transmitters in other cells communicating with different CBSDs also enter the first cell and interfere with the first signal. The first CBSD receives not only the first signal but also the unwanted co-channel signals resulting in problems in receiver performance. In addition to co-channel interference which occurs when the same channels or frequency spectrum are assigned to multiple CBSDs there is also an out of band or channel emission issue which is known as a signal leakage out of the frequency band or spectrum of operation. This emission is called adjacent channel interference and occurs when transmissions are sent on an adjacent channel, i.e., frequency, to the channel on which the CBSD is operating. While adjacent channel interference is a problem for both downlink and uplink wireless transmission, adjacent channel interference impacts uplink transmission from user equipment devices to CBSDs more than it does downlink wireless transmissions from CBSDs to user equipment devices since the transmission power for uplink transmissions is limited by the user equipment's maximum transmission power.
While the Spectrum Access Systems in CBRS networks currently assign or allocate frequency spectrum based on the co-channel interference level which each CBSD experiences at a particular geographical location, Spectrum Access Systems fail to take into account adjacent channel interference. That is Spectrum Access Systems attempt to optimize the assignment or allocations of frequency spectrum by assigning frequency spectrum or channels to the CBSDs so as to minimize the co-channel interference but do not take adjacent channel interference into account. By not taking adjacent channel interference into account when assigning or allocating frequency spectrum or channels to CBSDs, the Spectrum Access Systems are not making the most effective and efficient use of the limited frequency spectrum available in the CBRS network.
There is currently a technological problem in how to efficiently allocate resources, e.g., frequency spectrum, i.e., channel allocations, that efficiently and effectively utilize the limited frequency spectrum available to the CBRS network. There is also a current technological problem of how to take into account CBSD's traffic type in efficiently allocating frequency spectrum to CBSDs in CBRS networks to make efficient use of the limited frequency spectrum available. There is also a further need for new and/or improved methods and apparatus of allocating frequency spectrum in CBRS networks wherein the frequency spectrum is allocated based on feedback provided by CBSDs to the Spectrum Access System assigning spectrum to the CBSD. There is also a further technological problem of how to efficiently and effectively allocate frequency spectrum to CBSDs that account for adjacent channel interference being experienced by the CBSDs in addition to co-channel interference. One of the important objectives of the FCC is to utilize the available frequency spectrum in the CBRS network as efficiently and effectively as possible.
From the above it should be understood that there is a need for new and/or improved methods and apparatus for more efficiently assigning or allocating frequency spectrum or channels to CBSDs so as to reduce electromagnetic interference while optimizing CBSD devices coverage area and the quality of service for the user equipment devices being serviced by the CBSDs.